1. Field of the Invention
The present invention relates to an electronic musical instrument which generates waveforms electronically, and more particularly to an electronic musical instrument which produces musical sounds automatically without the operations of keys etc.
2. Description of the Prior Art
The progress of electronics has made it possible to electronically generate a musical sound waveform and to produce a musical sound with a loudspeaker. Apparatuses exploitating this technology are usually termed "electronic musical instruments". In general, the electronic musical instruments employ a method in which a musical sound to be produced is selected by a key. Further, they can produce the tone of a piano or any other musical instrument by assigning it with a lever switch or the like.
Since the electronic musical instrument selects musical sounds with keys as described above, the performance requires the technique of a piano and experience in the operations of the keys thereof. In other words, playing a person's accompaniment, for example, cannot be easily done and is possible for only those skilled in operating the electronic musical instrument. This signifies the problem that the conventional electronic musical instrument which is operated with keys cannot be simply played by anybody.
On the other hand, there are also apparatuses which convert a voice and produce the converted sound without using keys, for example, a musical sound signal conversion apparatus (Japanese Patent Application Publication No. 52-40973) which multiplies or demultiplies the fundamental frequency of a voice signal to produce a sound. In the Japanese Patent Application Publication, the fundamental frequency is obtained by detecting a zero-cross point of an input voice signal in an analogue manner. Thus, it is difficult to detect and process the input voice signal to produce the good musical sound.